Kapoor Ashish, Auer Dallas R, Lee Dongwon, Chatterjee Sumantra, Chakravarti Aravinda
McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Hum Mol Genet. 2017 May 15;26(10):1811-1820. doi: 10.1093/hmg/ddx084.
For most multigenic disorders, clinical manifestation (penetrance) and presentation (expressivity) are likely to be an outcome of genetic interaction between multiple susceptibility genes. Here, using gene knockouts in mice, we evaluated genetic interaction between loss of Ret and loss of Sema3d, two Hirschsprung disease susceptibility genes. We intercrossed Ret and Sema3d double null heterozygotes to generate mice with the nine possible genotypes and assessed survival by counting various genotypes, myenteric plexus presence by acetylcholinesterase staining and embryonic day 12.5 (E12.5) intestine transcriptome by RNA-sequencing. Survival rates of Ret wild-type, null heterozygote and null homozygote mice at E12.5, birth and weaning were not influenced by the genotypes at Sema3d locus and vice versa. Loss of myenteric plexus was observed only in all Ret null homozygotes, irrespective of the genotypes at Sema3d locus, and Sema3d null heterozygote and homozygote mice had normal intestinal innervation. As compared with wild-type mice intestinal gene expression, loss of Ret in null homozygotes led to differential expression of ∼300 genes, whereas loss of Sema3d in null homozygotes had no major consequence and there was no evidence supporting major interaction between the two genes influencing intestine transcriptome. Overall, given the null alleles and phenotypic assays used, we did not find evidence for genetic interaction between Ret and Sema3d affecting survival, presence of myenteric plexus or intestine transcriptome.
对于大多数多基因疾病而言，临床表现（外显率）和表现形式（表现度）很可能是多个易感基因之间遗传相互作用的结果。在此，我们利用小鼠基因敲除技术，评估了两种先天性巨结肠病易感基因Ret缺失和Sema3d缺失之间的遗传相互作用。我们将Ret和Sema3d双基因敲除杂合子进行杂交，以产生具有九种可能基因型的小鼠，并通过统计各种基因型来评估存活率，通过乙酰胆碱酯酶染色评估肌间神经丛的存在情况，以及通过RNA测序评估胚胎第12.5天（E12.5）肠道转录组。E12.5、出生和断奶时，Ret野生型、基因敲除杂合子和基因敲除纯合子小鼠的存活率不受Sema3d基因座基因型的影响，反之亦然。仅在所有Ret基因敲除纯合子中观察到肌间神经丛缺失，而与Sema3d基因座的基因型无关，并且Sema3d基因敲除杂合子和纯合子小鼠的肠道神经支配正常。与野生型小鼠肠道基因表达相比，基因敲除纯合子中Ret的缺失导致约300个基因的差异表达，而基因敲除纯合子中Sema3d的缺失没有重大影响，并且没有证据支持这两个基因之间存在影响肠道转录组的主要相互作用。总体而言，鉴于所使用的无效等位基因和表型分析，我们没有发现Ret和Sema3d之间存在影响存活率、肌间神经丛存在或肠道转录组的遗传相互作用的证据。
